Bit with detachable blade



1366- 1951 H. c. WILSON BIT WITH DETACHABLE BLADE Filed Dec. 11, 1946 INVENTOIQ Patented Dec. 11,1951

BIT WITH DETACHABLE BLADE Harry G. Wilson, Sherman Oaks, Calif'.,;assignorto Robert H. Clark, Los'Angeles, Calif.

Application December 11, 19.46,;Seria1 No. 715,423

6 Claims.

This invention has to do with a bit with a detachable blade and it is a general object of the invention to provide a bit having a .releasably fastening means that acts to dependably secure the cutting blade in place on the shank of the tool.

The bit of the present invention is of the detachable blade type such as is disclosed and claimed in my copending application entitled Bit with Interchangeable Blades, Serial No. 715,424, filed December 11, 1946. My present invention is concerned primarily with the mounting of the cutter head on the shank-and with the provision of a particularly effective means for securing the head in place on the shank.

It is a general object of my present invention to provide a positive driving engagement between the shank and head which engagement does not permit of any shifting or slipping of the head relative to the shank.

Another object of the present invention is to provide a fastening means for securing a cutting head on a shank, which means is not subject to wedging so tight or to becoming so set as to make it difiicult to dislodge the head from the shank.

A further object of the present invention is to provide a retaining or fastening means for a cutter head which operates when the head is in active position on the head carrier, which means involves a part projecting from the carrier to engage in a socket or recess provided ,for its reception in the cutter head.

Fig. ,1 is a side view of a bit embodying the present invention showing it in the course of being used to bore a hole throu h an object. Fig. 2 is an enlarged view of the structure taken as indicated by line 2-2 on Fig. 1. Fig. 3 is .a vertical sectional view taken substantially as indicated by line 33 on Fig. 2 with certain of the central partsbrokenaway. Fig. 4 is an end view of the structure, being a view taken. as indicated byline 4-4 on Fig. 3. Fig. 5 is an enlarged side elevation of the cutter head showing it detached from the shank and showing it in the position in which it appears in Fig. 1 of the drawings. Fig. 6 is a view similar to Fig. 3 showing a different form of the retaining means. Fig. 7 is an end view of the structure shown in Fig. 6, being a view taken as indicated by line 'l-l on Fig. 6, and Fig. 8 is a detailed view taken substantially as indicatedby line .8--8 on Fig. 6.. g

The tool of the present invention: involves, generally, three principal elements, namely a shank element A, a cutter head B, and a retain- 11 g. means C acting to releasably retain the. cut .ter head in operating position on. the shank element. The. shank element A involves, generally, an elongate shank ID, a head carrier .1 I at the outer or lower end of the shank, and a feed screw l2- projecti g beyond or. from. the head carrier. l l.

The shank l0. may be of any desired size, shape or length. However, ordinarily it is preferred that it be a simple elongate bar .or shaft, uniform in size throughout its length except possibly at its. upper. endwhere it is provided with a polygonal part 14 suitable for engagement by a suitable operating device or tool.

The carrier ll provided-to carry or support the cutter head Bis preferably an integral continuation of the shank l0, and in accordance with my invention I provide a driving engagement between the carrier H and the head B by making the carrier non-circular in cross section and by providing an opening through the head to receive the carrier, which opening corresponds in size and shape to the carrier. In the preferred form of the invention the carrier II is provided with one or more fiat sides l5 and in the form of the invention shown in Figs. 1 to 5, inclusive, the carrier is polygonal in .cross sec- .tion, in fact, it is square in cross section so that it has four equal sides I5.. I prefer to flatten or otherwise form the. sides lief the carrier ll so that: the carrier is somewhatv smaller in cross section than the shank l0, leaving a downwardly facing shoulder 16 at the lower end of the shank against which the cutter head 3 abuts when in place on the carrier.

In Figs. 6, 7 and 8 I show a carrier ll somewhatdifierentin form; than that just described, in that the. carrier is simply a, continuation of the round shank it, except that it has diametricall-y opposite flattened sides 4 5 The. feed-screw 12 projects downwardly from or beyond the head carrier Hand it. is preferably a tapered screw having a thread of such character as to properly bite into the material being drilled in order to act as a feed for the tool. The screw is preferably an integral continuation of thecarrier. In fact, as shown in the drawings, the shank lll carrier H and screw 12 are ,formed of onebody or length of material.

which faces in the direction in which the tool is rotated during operation. The head also has a depending spur 23 with a sharpened edge 24 which spur serves to make an annular cut in the material drilled so that the hole is defined ahead of the edge 22 leaving the edge to merely shave the top from a boss-like projection 25 formed by the spur The head shown in the drawings is also provided with a clearance opening or throat 26 immediately forward of the lip 2| so that chips established or formed by the cutting edge freely pass the head and do not clog the tool. In the particular case illustrated the edge 22 and the clearance throat adjacent it extend from a point at or near the carrier H of the shank element to the periphery 2|! of the cutter head.

The central opening 30 provided in the cutter head B to receive the carrier not only fits or corresponds in shape to the carrier II but it is' centrally located in the disc-like head and is pitched or inclined so that when the head is on the carrier it is pitched or inclined from a plane normal to the longitudinal axis of the tool. The spur 23 depends from the lowermost part of the head, as clearly shown throughout the drawings.

The means that I provide for retaining the head on the carrier involves, broadly, a coupling member carried by one of the connected parts to engage in a socket or recess of the other of the parts. In the preferred arrangement the coupling member is carried by the shank element and engages a socket or recess in the head B. In the form of the invention illustrated in Figs. 1 to 5, inclusive, the coupling member is in the nature of a screw 40 carried by the shank element to be operated so that it extends into a socket or recess 4| in the wall of the opening 30 in the head B. The screw 4|! is threaded inan opening 42 which extends diametrically through the shank element and which is inclined or pitched so that one end opens at the carrier while the other end opens at a point at the side of the shank I above the carrier The screw 4|] has an outer end accessible at the exterior of the structure which outer end is preferably finished or formed to receive a suitable operating tool. In the case illustrated I have shown a slot 44 in the outer end of the screw suitable for reception of a screw driver or the like. The inner end 45 of the screw which occurs at the carrier I is pointed or beveled'and the socket 4| in the head which receives the end 45 of the screw is correspondingly'pitched so that the end of the screw seats effectively in the socket 4|, as clearly shown in Fig. 3 of the drawings.

When the screw is in the operating or advanced position shown in the drawings the pointed end thereof extends into the recess 4| positively holding the head B on the carrier H with the head in engagement with the shoulder I6 at the end of the shank I0. To release the head B it is merely necessary to rotate the screw so that the end 45 is withdrawn from the recess 4|, whereupon the head can be freely slid from the carrier II.

In the form of the invention illustrated'in Figs. 6, '7 and 8 of the drawings the coupling member is in the nature of a detent preferably a ball 4|! carried in an opening 42 in the shank element of the tool. The ball 4!] normally projects from the carrier I? to enter 'a socket 4| provided in the opening 30 formed through the headto receive the carrier. The opening 42" in the shank element is preferably a socket of 4 suitable depth to properly accommodate a spring 50 that acts to normally yieldingly urge the ball 4|] outwardly. It will be understood that the mouth of the socket may be slightly contracted or peened over to retain the ball against displacement from the socket, yet allowing it to project enough to enter the recess 4| as shown in Fig. 6 of the drawings. This particular form of coupling means possesses certain advantages over that first described. For example it does not require any manipulation upon the part of the operator since the ball snaps into and out of operating position as the cutter head is forced onto or from the carrier of the shank element.

From the foregoing description it will be apparent that I have provided a mounting for a cutter head wherein the head is positively driven from the shank element independently of the means employed to retain the head on the shank element. Consequently, the retaining means is not subject to excessive strains and need only be sufficiently heavy or sturdy to hold the head on the carrier portion of the shank. In the form of the invention first described the screw 40 is, in effect, a locking element requiring definite manipulation by the operator before the head can be released, whereas the form last described is a yielding means permitting the head to be withdrawn whenever sufficient withdrawing force is applied.

Having described only typical preferred forms and applications of my invention, I do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to myself any variations or modifications that may appear to those skilled in the art and fall within the scope of the following claims.

Having described my invention, I claim:

1. A bit of the character described including, a cutter head with a cutting edge, a shank element having an elongate shank and a head carrier on the shank fitting an opening in the head to establish driving engagement between the shank element and head, and means releasably retaining the head on the carrier including a screw carried by the shank element extending into a socket in the head, the screw being threaded in an inclined opening in the shank element so one end opens at the head carrier while the other opens above the head carrier.

2. A bit of the character described including, a substantially fiat cutter head with a cutting edge, a shank element having an elongate shank and a head carrier on the end of the shank fitting an opening in the head to establish driving engagement between the shank element and head, the axis of the opening in the head being inclined relative to a line perpendicular to the plane of the head, and means releasably retaining the head on the carrier including a member carried by the shank element shiftable relative to the shank and extending into a socket in the head the periphery of the head being concentric with the shank.

3. A bit of the character described including, a substantially flat cutter head with a cutting edge, a shank element having an elongate shank and a flat sided head carrier on the end of the shank fitting an opening in the head to establish driving engagement between the shank element and head, the axis of the opening in the head being inclined relative to a line perpendicular to the plane of the head, and the shank element having an inclined shoulder engaged by the head when the head is on the carrier, and

head to releasably hold the head on said portion.

5. A bit of the character described including, a substantially fiat cutter head having a cutting edge and a central inclined opening, a shank element including an elongate shank, a flat sided cutter head carrier at the outer end of the shank and engaged in said opening to have driving engagement with the head and a feed screw projecting from the carrier, and a member threaded in a transverse inclined opening in the shank element and extending into a socket in the head to releasably retain the head on the carrier.

6. A bit of the character described including, a substantially flat cutter head having a central inclined polygonal opening and a cutting edge, a shank element including an elongate shank, a polygonal head carrier at the outer end of the shank and engaged in the said opening to have driving engagement with the head, an inclined shoulder on the shank element supporting the head inclined relative to the shank and a feed screw projecting from the carrier, and a screw member carried in an inclined transverse opening in the shank element and extending into a socket in the head to releasably retain the head on the carrier the screw member being accessible at the portion of the head that extends downwardly from the shank, and the periphery of the head being concentric with the shank and having a depending spur at its lowermost part.

HARRY C. WILSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 21,179 Barnes Aug. 17, 1858 74,490 Bidwell Feb. 18, 1868 275,391 Jones Apr. 10, 1883 915,080 Dixson et al Mar. 16, 1909 1,412,718 Straehle Apr. 11, 1922 1,918,202 Wiehagen July 11 1933 

